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September 15, 2014

September 15, 2014

Posted by **lily** on Tuesday, October 13, 2009 at 8:52pm.

Simplifying equations confuses me easily.

- math -
**Ms. Sue**, Tuesday, October 13, 2009 at 8:55pm7(y+3)+2y

7y + 21 + 2y

9y + 21

- math -
**Tasuba**, Tuesday, October 13, 2009 at 8:56pm7(y+3)-2y

multiply 7 with y and 3

7y+21-2y

collect like terms

7y-2y+21

5y+21

Done

- math -
**Ms. Sue**, Tuesday, October 13, 2009 at 8:57pmTasuba -- I think you've misread the problem. I don't see any minus signs in the original problem.

- math -
**Christiaan**, Tuesday, October 13, 2009 at 9:01pmThe first thing you should do is try to remove the brackets. You can do this by using distributivity. In symbols, this means the following:

a*(b + c) = a*b + a*c

As you can see, the first term of the equation is 7*(y+3)

So, using distributivity, we find that

7*(y+3) = 7*y + 7*3 = 7y + 21

So, the equation can be simplified in the following manner:

7(y+3)+2y = 7y + 21 + 2y

Now, we have to terms with y. if we put them together, we get:

7y + 2y + 21

If we use the formula of distributivity in reverse, we find that:

7y + 2y = (7+2)*y = 9y

So, the equation can be further simplified in the following manner:

7y+2y+21 = 9y + 21

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